Sized glass fibers maintained in a layered relationship by urea-formaldehyde binders and suitable for wet-laid, non-woven fibrous mat are well known. Such mats can be treated to manufacture roofing felts for shingles and built-up roof applications.
The admixture of urea-formaldehyde resins with styrene-butadiene latex copolymers and acrylamide type monomers to improve binder flexibility and moisture resistance in glass fiber mat has been disclosed in U.S. Pat. No. 4,258,098 to Bondoc et al.
There has now been invented an improvement of those binders in respect to moisture resistance.
This invention is directed to that improvement.